反应详情

A mixture of N-methyl-o-phenylenediamine dihydrochloride (10.80g. 0.005 mol) and cyanoguanidine (9.30g, 0.11 mol) was heated under reflux in water (80 ml) for 21/2 hours. The reaction mixture was cooled, basified with excess 40% sodium hydroxide, and the resulting precipitate filtered, washed with water and dried in vacuo. (7.19g; m.p. 142°-146°C). This was dissolved in excess dilute hydrochloric acid and evaporated in vacuo. The crude hydrochloride was recrystallised from ethanol/ether to yield 2-guanidino-1-methylbenzimidazole dihydrochloride (600g; 42%) as off-white micro-crystals m.p. 228°-238°C.

1. temperaturewas heated
2. temperatureThe reaction mixture was cooled
3. filtrationthe resulting precipitate filtered
4. washwashed with water
5. customdried in vacuo
6. dissolutionThis was dissolved in excess dilute hydrochloric acid
7. customevaporated in vacuo
8. customThe crude hydrochloride was recrystallised from ethanol/ether